1. Field of the Invention
This invention relates to an engine for a motor vehicle, particularly for a motorcycle or four-wheeled automobile. More particularly, it is concerned with a multi-cylinder engine having compact and light weight structure.
2. Description of the Prior Art
A motor land vehicle, for example, motorcycle or automobile, calls for a light and compact multi-cylinder engine which satisfies the requirements for decreased vibration, fuel economy and improved acceleration. Various proposals have hitherto been made to provide an improved multi-cylinder engine.
There is, for example, known an engine having a plurality of cylinders disposed in mutually staggered relationship. In such an engine, however, crank gears b of the respective cylinders are connected to a gear e integral with a flywheel on an output shaft by connecting gears c and d, as shown in FIG. 1 (Prior Art). This arrangement makes it difficult to reduce the distance between the crankshafts in a plane perpendicular to the cylinder centerlines. Further, since the engine employs a crankcase assembly divided in a horizontal plane, it is necessary to position the crankshafts a in alignment with a main shaft f and a counter shaft g of a transmission system in a common plane. This requires a lot of connecting gears, and a long crankcase assembly. Therefore, it has hitherto been difficult to obtain a light and compact multi-cylinder engine.
A typical multi-cylinder engine having a plurality of cylinders disposed in mutually staggered relationship is shown in U.S. Pat. No. 4,194,469.